15 and 16 The phytochemicals Vandetanib induce toxicity in tumor cells either by scavenging constitutive reactive oxygen species or by generating paradoxically additional amount of free radicals resulting in the imbalance of cellular oxidative status, leading to inhibition of cell proliferation and eventually cell death.17, 18 and 19 In a recent study,20 the bark extract of S. oleosa was examined for its cytotoxic potential against different cell lines such as 502713 (colon), SW-520 (colon), HCT-13 (colon), A-549 (lungs), HEP-2 (liver), SK-NS-H (central nervous system), and IMR-32 (neuroblastoma). SRB dye assay following the method of Skehan et al 21 is used to evaluate the cytotoxic potential. The

ethyl acetate, methanol, and water extract showed a significant cytotoxicity against all selleckchem cell lines, except the IMR-32 cell line whereas hexane and chloroform extract did not show any significant inhibition against any of the cell lines. The cytotoxic potential was correlated with their hydroxyl radical scavenging potential. Hexane and chloroform extracts were found to have least hydroxyl radical scavenging ability, hence least cytotoxicity against the different cell lines. Oxygen is used for generating

metabolic energy in our body but it also produces reactive oxygen species as by product during its various reactions in the body. Reactive oxygen species are usually atoms or a group of atoms having odd (unpaired) electrons, in aerobic cells these are produced during mitochondrial electron transport and several Thymidine kinase oxidation reactions.22

These reactive species can, react with DNA and several other biomolecules causing what is called ‘oxidative damage to DNA’ This damage causes changes in DNA such as strand breaks; changes at cross links between DNA and protein; changes at base free sites among other changes.23 Several medicinal plants, fruits, vegetables can decrease the risk of oxidative damage as they comprise of vitamins, carotenes, phenolic compounds, flavanoids, alkanoids, tannins etc. which act as chemopreventive agents.24, 25 and 26 These phytochemicals can prevent damage by their radical scavenging ability. Thind et al evaluated the hydroxyl radical scavenging potential of S. oleosa. Extracts of roots of S. oleosa with different solvents were tested for their antiproliferative activity. Methanol extract was effective against a colon cell line (SW-620), ethyl acetate against SK-NS-H (CNS cell line) and water extract against 502713 and SW-620 (colon) cell lines. Hydroxyl radical which was used to determine radical scavenging potential of extracts, was generated by Fenton’s reaction, in site-specific and non-site-specific deoxyribose degradation assays. The extracts showed radical scavenging potential following the order of inhibition at 100 μg/mL as ethyl acetate extract (67.72%) > water extract (65.68%) > methanol extract (64.32%) in site-specific assay and as methanol extract (83.38%) > ethyl acetate extract (81.